# -*- coding: utf-8 -*-
# @File    : mercator.py
# @Author  : LVFANGFANG
# @Time    : 2018/7/7 0007 13:34
# @Desc    : 墨卡托坐标与百度经纬度坐标相互转换

import math

MCBAND = [12890594.86, 8362377.87, 5591021, 3481989.83, 1678043.12, 0]
LLBAND = [75, 60, 45, 30, 15, 0]
MC2LL = [
    [1.410526172116255e-8, 0.00000898305509648872, -1.9939833816331, 200.9824383106796, -187.2403703815547,
     91.6087516669843, -23.38765649603339, 2.57121317296198, -0.03801003308653, 17337981.2],
    [- 7.435856389565537e-9, 0.000008983055097726239, -0.78625201886289, 96.32687599759846, -1.85204757529826,
     -59.36935905485877, 47.40033549296737, -16.50741931063887, 2.28786674699375, 10260144.86],
    [- 3.030883460898826e-8, 0.00000898305509983578, 0.30071316287616, 59.74293618442277, 7.357984074871,
     -25.38371002664745, 13.45380521110908, -3.29883767235584, 0.32710905363475, 6856817.37],
    [- 1.981981304930552e-8, 0.000008983055099779535, 0.03278182852591, 40.31678527705744, 0.65659298677277,
     -4.44255534477492, 0.85341911805263, 0.12923347998204, -0.04625736007561, 4482777.06],
    [3.09191371068437e-9, 0.000008983055096812155, 0.00006995724062, 23.10934304144901, -0.00023663490511,
     -0.6321817810242, -0.00663494467273, 0.03430082397953, -0.00466043876332, 2555164.4],
    [2.890871144776878e-9, 0.000008983055095805407, -3.068298e-8, 7.47137025468032, -0.00000353937994,
     -0.02145144861037, -0.00001234426596, 0.00010322952773, -0.00000323890364, 826088.5]
]
LL2MC = [
    [- 0.0015702102444, 111320.7020616939, 1704480524535203, -10338987376042340, 26112667856603880, -35149669176653700,
     26595700718403920, -10725012454188240, 1800819912950474, 82.5],
    [0.0008277824516172526, 111320.7020463578, 647795574.6671607, -4082003173.641316, 10774905663.51142,
     -15171875531.51559, 12053065338.62167, -5124939663.577472, 913311935.9512032, 67.5],
    [0.00337398766765, 111320.7020202162, 4481351.045890365, -23393751.19931662, 79682215.47186455, -115964993.2797253,
     97236711.15602145, -43661946.33752821, 8477230.501135234, 52.5],
    [0.00220636496208, 111320.7020209128, 51751.86112841131, 3796837.749470245, 992013.7397791013, -1221952.21711287,
     1340652.697009075, -620943.6990984312, 144416.9293806241, 37.5],
    [- 0.0003441963504368392, 111320.7020576856, 278.2353980772752, 2485758.690035394, 6070.750963243378,
     54821.18345352118, 9540.606633304236, -2710.55326746645, 1405.483844121726, 22.5],
    [- 0.0003218135878613132, 111320.7020701615, 0.00369383431289, 823725.6402795718, 0.46104986909093,
     2351.343141331292, 1.58060784298199, 8.77738589078284, 0.37238884252424, 7.45]
]


def mercator_to_lnglat(mlnglat):
    abslnglat = {
        'lng': math.fabs(mlnglat['lng']),
        'lat': math.fabs(mlnglat['lat'])
    }

    for i in range(len(MCBAND)):
        if (abslnglat['lat'] >= MCBAND[i]):
            mc = MC2LL[i]
            break

    lnglat = convertor(mlnglat, mc)
    lnglat = {
        'lng': round(lnglat['lng'], 6),
        'lat': round(lnglat['lat'], 6)
    }

    return lnglat

def lnglat_to_mercator(lnglat):
    mc = []
    lng = getLoop(lnglat['lng'], -180, 180)
    lat = getRange(lnglat['lat'], -74, 74)
    for i in range(len(LLBAND)):
        if lat >= LLBAND[i]:
            mc = LL2MC[i]
            break
    if mc:
        for i in reversed(range(len(LLBAND))):
            if lat <= - LLBAND[i]:
                mc = LL2MC[i]
                break
    return convertor({'lng': lng, 'lat': lat}, mc)

def convertor(point, mc):
    if not point or not mc:
        return

    lng = mc[0] + mc[1] * math.fabs(point['lng'])
    c = math.fabs(point['lat']) / mc[9]
    lat = mc[2] + mc[3] * c + mc[4] * c * c + mc[5] * c * c * c + mc[6] * c * c * c * c + mc[7] * c * c * c * c * c + \
          mc[8] * c * c * c * c * c * c

    tmp = -1 if point['lng'] < 0 else 1
    lng *= tmp

    tmp = -1 if point['lat'] < 0 else 1
    lat *= tmp

    return {'lng': lng, 'lat': lat}


def getLoop(lng, minimum, maximum):
    while (lng > maximum):
        lng -= maximum - minimum
    while (lng < minimum):
        lng += maximum - minimum
    return lng


def getRange(lat, minimum, maximum):
    if minimum:
        lat = max(lat, minimum)
    if maximum:
        lat = min(lat, maximum)
    return lat


if __name__ == '__main__':
    print(mercator_to_lnglat({'lng': 12672289.52, 'lat': 2524478.36}))
    print(lnglat_to_mercator({'lng': 113.835875, 'lat': 22.243608}))
